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Understanding Left Arm Weakness and Heaviness: Potential Causes and Diagnoses
Left arm weakness and heaviness can be alarming symptoms with a variety of underlying causes. This article synthesizes findings from multiple case studies to provide a comprehensive overview of potential diagnoses.
Ischemic Stroke and Carotid Artery Web
One significant cause of sudden left arm weakness is an ischemic stroke, which can result from a carotid artery web. A case study of a 67-year-old man revealed that his left arm weakness was due to an acute infarct in the right frontal lobe, affecting the motor cortex. This was linked to a carotid web causing stenosis in the right internal carotid artery. The patient experienced a recurrence of symptoms, which led to the discovery of a new occlusion in the right middle cerebral artery, necessitating endovascular treatment.
Musculocutaneous Neuropathy
Another potential cause is musculocutaneous neuropathy, often resulting from physical trauma. A 33-year-old male chef experienced progressive left arm weakness after feeling a "pop" in his biceps while lifting a heavy pan. This was followed by muscle atrophy and weakness, particularly during weighted flexion exercises. The physical examination showed decreased muscle bulk and strength in the left biceps, indicating musculocutaneous neuropathy.
Brachial Plexopathy and Knapsack Palsy
Brachial plexopathy, including conditions like knapsack palsy, can also lead to left arm weakness. A 16-year-old boy developed left arm weakness after carrying a heavy backpack, which led to muscle atrophy and weakness in the deltoid, biceps, and periscapular muscles. This condition, often caused by compression of the brachial plexus, can result in significant muscle weakness and atrophy. Similarly, a 28-year-old law student developed posterior interosseous nerve palsy from carrying a heavy knapsack, leading to left hand weakness.
Tumors and Neurological Conditions
Tumors can also present with left arm weakness. A 47-year-old woman experienced sudden left arm and hand weakness, along with facial droop and dysarthria. MRI scans revealed a contrast-enhancing tumor, which was the underlying cause of her symptoms. Additionally, a 31-year-old woman with a history of neck, back, and arm pain following an injury also presented with left arm weakness, highlighting the importance of considering soft tissue injuries and tumors in the differential diagnosis.
Progressive Neurological Disorders
Progressive neurological disorders can manifest as left arm weakness. A 25-year-old man reported progressive left arm weakness over several months, with muscle atrophy and decreased grip strength. This case underscores the need for thorough neurological evaluation to rule out progressive conditions. Similarly, a 68-year-old man with multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) presented with chronic left arm weakness, pseudoathetosis, and sensory deficits, indicating a complex neuropathic condition.
Conclusion
Left arm weakness and heaviness can stem from various causes, including ischemic stroke, neuropathies, brachial plexopathy, tumors, and progressive neurological disorders. Accurate diagnosis requires a comprehensive clinical evaluation, including imaging and neurological assessments, to identify the underlying cause and guide appropriate treatment.
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